Measurement of Weight 55 



before use. Should the number on one side, however, 

 exceed that on the other by more than 2 or 3 divisions, 

 the milled nut at the end of the beam is turned on its 

 rod till the pointer swings evenly on each side of the 

 centre of the scale. 



Exercise for Student. 



In which direction must the nut at the right-hand end of the 

 beam travel if the pointer swings too far to the right, showing that 

 the left side of the balance is slightly the heavier ? Apply the 

 Principle of Moments. 







While adjusting the balance, and while adding 

 bodies to, or removing them from, the pans, always 

 put the balance out of action. This precaution prevents 

 undue wear and tear of the knife-edges, upon the 

 proper condition of which the accuracy of the weighings 

 obtained largely depends. 



When the balance is in proper adjustment, place 

 a penny on the left-hand pan. Open the box of 

 weights and remove from it, with the forceps supplied 

 with the box, a weight estimated to be greater than 

 that of the penny. Place this on the right-hand pan 

 and gently raise the arrest ment with the left hand. 

 Note the direction of swing of the pointer. If the 

 weight prove too heavy, put the balance out of action, 

 remove the weight, and replace it by the next smaller 

 weight. Again raise the arrestment and note the 

 indication of the pointer. Continue adding weights to, 

 or removing them from, the right-hand pan, as directed 

 by the pointer indications, dealing with them in the 

 descending order of magnitude in which they are 

 arranged in the box, till the smallest weight is reached, 

 and the pointer swings nearly evenly on each side of 

 the middle point of the scale. If the balance is cased, 

 the front should now be lowered, the arrestment again 



